1. Field of the Invention
The present invention relates to an apparatus for measuring the velocity of a chemical reaction in which light absorbance changes in proportion to time.
2. Description of the Prior Art
An example of such reaction is enzymatic reaction. The determination of activity of an enzyme from a reaction thereof is usually realized by multiplying the change in absorbance in one minute (difference of absorbance/time) by a constant (hereinafter expressed as K factor) determined by the substances and conditions of measurement involved.
Also it is possible to obtain said value of the difference of absorbance/time for one minute by conversion from measurements separated by an arbitrary time interval.
In the case of enzymatic reaction, however, there usually exists a certain initial non-linear phase, called a lag phase, after the start of the reaction, and the linear reaction is reached only after such lag phase, as shown in FIG. 2 wherein the absorbance is shown as the ordinate plotted against time shown as the abscissa. For the exact determination of enzymatic activity, the measurements have to be carried out in such linear reaction portion. In the prior art the duration of such lag phase has been determined empirically and the measurements have been effected after the lapse of such duration. In such method, however, there have been no way to detect eventual error resulting from measurements being erroneously made during such non-linear period due to possible fluctuation of samples. Further such error can only be detected by checking the difference of absorbance by means of repeating plural same measurements, which inevitably lead to a drawback of longer measuring time.
The object of the present invention, therefore, is to provide an apparatus for measuring the reaction velocity which measures the absorbances A.sub.1 and A.sub.2 at times t.sub.1 and t.sub.2 to determine the difference of absorbance .DELTA.A, and simultaneously identifies and indicates whether such measurements are effected in the linear portion of the reaction.